Background

The reductions of perioperative blood loss and inflammatory response are important in total knee arthroplasty. Tranexamic acid reduced blood loss and the inflammatory response in several studies. However, the effect of epinephrine administration plus tranexamic acid has not been intensively investigated, to our knowledge. In this study, we evaluated whether the combined administration of low-dose epinephrine plus tranexamic acid reduced perioperative blood loss or inflammatory response further compared with tranexamic acid alone.

In this study, a biomimetic triphasic scaffold was constructed to mimic the native cartilage-subchondral bone tissue structure. This scaffold contained chondral layer, calcified zone of cartilage (CZC) and subchondral bone layer. The chondral layer was type II collagen sponge, the CZC and the subchondral bone layer were derived from normal pig knee by decellularization. In order to build separate microenvironment for chondral layer and subchondral bone layer, a dual-chamber bioreactor was designed by computer aided design, manufactured by 3D printer using Poly Lactic Acid, with CZC as the barrier of these two chambers. Culture medium in these two chambers was circulated separately by peristaltic pumps. Amniotic mesenchymal stem cells were seeded in this scaffold, fluorescence labeling was used for cell tracking, total DNA content analysis was used to indicate cell proliferation, and inducing medium was used to direct stem cells differentiation. After 7 days culture, the cells regularly distributed in the scaffold, cell adhesion and proliferation was not affected. No cell migration across CZC occurred. Total DNA content analysis showed that cells in scaffold increased in a time-dependent manner. Chondrogenic and osteogenic medium could induce stem cells in these two chambers to differentiate into chondrocytes and osteocytes, respectively. Our pilot study showed that the dual-chamber culture system with biomimetic triphasic scaffold was feasible, therefore this system will be further modified and tested in vivo.

Articular cartilage repair remains a challenge in orthopedic surgery, as none of the current clinical therapies can regenerate the functional hyaline cartilage tissue. In this study, we proposed a one-step surgery strategy that uses autologous bone marrow mesenchymal stem cells (MSCs) embedded in type II collagen (Col-II) gels to repair the full thickness chondral defects in minipig models. Briefly, 8 mm full thickness chondral defects were created in both knees separately, one knee received Col-II + MSCs transplantation, while the untreated knee served as control. At 1, 3 and 6 months postoperatively, the animals were sacrificed, regenerated tissue was evaluated by magnetic resonance imaging, macro- and microscopic observation, and histological analysis. Results showed that regenerated tissue in Col-II + MSCs transplantation group exhibited significantly better structure compared with that in control group, in terms of cell distribution, smoothness of surface, adjacent tissue integration, Col-II content, structure of calcified layer and subchondral bone. With the regeneration of hyaline-like cartilage tissue, this one step strategy has the potential to be translated into clinical application.